286 



WHITTAKER AND LIKENS 



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PRECIPITATION, mm 



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Fig. 2 Annual dry-matter productivity vs. mean annual precipitation. 



34 



worldwide prediction. Lieth 34 (compare also Refs. 3—6) has used the technique 

 to prepare a map of net annual primary production of the land surface, shown in 

 Fig. 3. The map implies production values for the land close to those of Table 1 ; 

 the two approaches should of course largely agree since they use different ways 

 of averaging some of the same production data. Despite the relation of marine 

 production to nutrient levels that Steele, 69 Riley, 54 and others have sought to 

 model, there is no comparable treatment of the oceans. 



Biomass data are somewhat less amenable to this treatment than are 

 production data. In general, on both land and sea, biomass is correlated with 

 productivity; but these correlations are loose. The relation may be expressed as a 

 biomass-accumulation ratio — the ratio of biomass present in living organisms to 

 net annual primary productivity, both in dry matter or carbon per unit area 

 (Table 1, column 7/column 3). The reciprocal ratio of production to biomass is 

 sometimes used; but this less effectively expresses some of the relations of 

 interest, particularly the correlations of biomass accumulation with size and 

 longevity of dominant organisms, the consequent time scale of community 

 stability, development of community structure and diversity of niche offered 

 small animals, size of nutrient pools in organisms, and extent of environmental 

 modification by the community. The time spent by organic matter in plants 

 varies widely for different tissues, but the biomass-accumulation ratio may be 

 taken as an average "residence time" in years for carbon or organic matter in the 

 plant community. Normal ranges of such biomass-accumulation ratios on land 



